What is Wheatstone Bridge

The Wheatstone bridge is a circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, where the other two legs have known resistances. It was invented by Sir Charles Wheatstone in 1833 and is widely used in modern electrical engineering applications.

The circuit consists of four resistors, forming a diamond shape. The two opposite vertices of the diamond are connected to a voltage source, and the other two vertices are connected to a detector or a measuring instrument. One of the resistors in the bridge is an unknown resistor, and the other three resistors are known.

By adjusting the value of one of the known resistors, the bridge can be balanced, resulting in zero voltage difference between the detector terminals. This balance point can then be used to calculate the value of the unknown resistor, based on the values of the other three resistors and the voltage applied to the bridge.

The Wheatstone bridge is commonly used in electronic circuits for measuring resistance, strain, temperature, and other physical quantities. It is also used in sensors and transducers, as well as in strain gauge and pressure transducer circuits.

Calculations

Other

The Wheatstone bridge is used to measure an unknown resistance by balancing two legs of a bridge circuit against the other two legs with known resistances. The unknown resistance can be calculated using the following formulas:

1. Balance equation:

R1/R2 = Rx/R3

where R1, R2, R3 are the known resistors and Rx is the unknown resistance.

2. Calculation of unknown resistance:

Rx = R2 * (R3/R1)

or

Rx = R1 * (R2/R3)

where Rx is the unknown resistance, R1, R2, and R3 are the known resistances.

3. Sensitivity equation:

S = ΔVout/ΔRx = (R2/R1+R2) – (R3/R4+R3)

where S is the sensitivity, ΔVout is the change in output voltage due to a change in Rx, ΔRx is the change in the unknown resistance, R1, R2, R3, and R4 are the four resistors in the bridge.

These formulas can be used to design and analyze Wheatstone bridge circuits for various applications.